If you want to trace the history of waterjet cutting, it can be followed to the Soviet Union and New Zealand at hydraulic mining of coal industry. People used streamed water and aimed it to the blasted rock face in order to carry away the loose coal and rock to reduce workload. This working method was also used in South African gold mines and redeveloped to remove unuseful rock from the work area into a collection drift or tunnel. From 1853 to 1886, during the California Gold Country, the water was firstly pressurized and used to peel soft gold rock from the mining surfaces. With this pressurized water, miners can stand further back from the washed rock. This method was much safer than before and became popular, because of it could keep danger from collapsing walls and blasted rocks. By early 1900s, this method of mining had used by Prussia and Russia in washing blasted coal away.
In the 1930s, Russia made the first “waterjet” attempt at cutting the rock with the pressurized water. This water cannon could generate a pressure of 7000 Bars.
In the 1970s, this technology was developed to be capable of creating a 40,000 Bar pressure in the USA. However, most of the waterjet mining was growth after combining a drill with the waterjet. Until 1972, Professor Norman Franz of Michigan working with McCartney Manufacturing Company installed the first industrial waterjet cutter. The equipment was installed in Alton Boxboard. As the same period, Flow industries also began to market industrial waterjet cutting equipment. Flow Industries added sand as an abrasive waterjet and it could cut through metal and ceramics. From there, the waterjet cutting industry took off from waterjet mining.
Most waterjet cutting theories are almost same. They all explain the waterjet cutting like a form of micro erosion that a large volume of water go through a small orifice in the nozzle.
The water traveling through a reducing narrow orifice by a constant volume will cause the water particles’ speed to rapidly accelerate. This accelerated water stream leaving the nozzle impacts on the material to be cut. Under the extreme pressure of the accelerated water particles, the a small area of the work impacting place will generate small cracks until the material is cut through.
Waterjet cutting uses only a pressurized stream of water to cut through material. It also called pure-water waterjet cutting. This type of cutting is limited to material with naturally occurring small cracks or softer material.
Slurry: An abrasive waterjet slurry system mixes the abrasive with the water jet early in the system. This is done before the water is pressurized. Slurry systems then accelerate the abrasive particles with the water throughout the system. This causes more wear on the internal parts than an entrainment system. Entrainment:
An abrasive waterjet entrainment system mixes the abrasive with the waterjet in a mixing chamber just after the nozzle. In most systems being built today, a venturi effect is utilized to pull the abrasive into the waterjet. The abrasive particles are accelerated into the stream and then with the stream out the orifice.
Abrasive Water Suspension Jets:
An abrasive water suspension jet system accelerates a suspension of abrasive in water through the system. This type of system appears to be more efficient than previously developed abrasive waterjet systems. *NOTE: Southwest Research Institute has patented a water/gel (SUPER-WATER (R)) abrasive system that cuts 0.006″ wide. The intended use of this system is for micro machining. SUPER-WATER (R) was developed by Berkeley Chemical Research, Inc., and has been found better then water in many applications from cutting to cleaning.
Basic Equipment Used
1. CNC guide machine
2. PC based programmable controller or microprocessor based control
3. Structural steel Base (optional)
4. Servo drive system
5. “X/Y” carriage
6. Cantilever arm/bridge
7. Motorized “Z” axis
8. Catch tank
9. Waterjet Cutting table
10. Work piece support grid/material
11. Filtration system (optional)
12. High pressure pumps
13. Pressure intensifiers
14. Abrasive material disposal/removal system
15. Injector to draw abrasives into cutting stream
16. Mixing chamber
17. Cutting nozzle (varying orifice size)
18. Abrasive removal system(optional)
19. Chiller (optional)
More information about waterjet parts and waterjet accessories please click here.Waterjet products.
The information about waterjet applications, please click here. Waterjet application.
The Disadvantages and Advantages to Waterjet Cutting
Waterjet cutting, this machining process is so widely useful that it can substitute many other cutting methods readily. However, this cutting method still has a few limitations. The listing below is these few limitations and a brief description of each.
One of the main disadvantages of waterjet cutting is that a limited number of materials can be cut economically. Although, it is possible to cut many hard materials like tool steels, the cutting rate will have to sharply reduce, which means the time to cut a part will be extended much longer. Because of this, the advantages of waterjet cutting will be costly and outweigh.
The other disadvantage is cutting thick parts may lost accuracy and materials. When the part is too thick, the water jet will cut on a diagonal, or having a wider cut at the bottom side than the top side. It can also cause a ruff wave pattern on the cut surface and lost materials at bottom parts.
Another disadvantage is taper but right now has been improved. This problem exists in cutting thick materials. Taper is when the jet exits the part at a different angle than it enters the part, and can cause dimensional inaccuracy. Decreasing the speed of the head or increasing pump pressure may reduce this, although it can still be a problem and will increase the cost. Nowadays, if using 4-axis cutting head or 5-axis cutting head, the taper would not a problem any more. More information about cutting head to avoid taper please click here. Waterjet cutting head.
There are many reasons decide waterjet cutting is a preferable cutting methods than over others. The below listing is several advantages with a brief explanation of each.
No heat generated. In waterjet cutting process, no heat generated is especially useful for cutting materials and other cutting methods may issue excessive heat during process may change the properties of the material.
Unlike machining or grinding, waterjet cutting does not produce any dust or particles that are harmful if inhaled.
The kerf width in waterjet cutting is very small, and very little material is wasted.
Waterjet cutting can be easily used to produce prototype parts very efficiently. An operator can program the dimensions of the part into the control station, and the waterjet will cut the part out exactly as programmed. This is much faster and cheaper than drawing detailed prints of a part and then having a machinist cut the part out.
Waterjet cutting can be easily automated for production use.
Waterjet cutting does not leave a burr or a rough edge, and eliminates other machining operations such as finish sanding and grinding.
Waterjets are much lighter than equivalent laser cutters, and when mounted on an automated robot. This reduces the problems of accelerating and decelerating the robot head, as well as taking less energy.
More information about waterjet advantages please click here. Why choose waterjet.